Human fingerprint is an innate, unique, and invariant feature that can be used for distinguishing individuals. A fingerprint includes patterns, which are aggregate characteristics of ridges and furrows on the skin surface of a finger. The three basic patterns of fingerprint ridges are the arch, loop, and whorl. A fingerprint pattern can include many minutia features, such as ridge endings, ridge bifurcations, arches, tented arches, left-handed whorls, right-handed whorls, double whorls, and other details, which can determine the uniqueness of the fingerprint pattern.
Along with the development of the pattern recognition theories, many fingerprint recognition apparatus have been developed. However, the existing fingerprint recognition apparatus are usually not thin enough to meet market demand.